Big Iron: A firearm, specifically a revolver. Due to the thick metal used in creating old-style revolvers such as the Colt Peacemaker or the newer Ruger Blackhawk/Redhawk, and partially due to the weight of the weapon, they earned the nickname "Big Iron." This phrase became largely popular after Marty Robbins' widly successful gunfighting ballad called "Big Iron."

A colloquism from the American Frontier days, referring to a handgun with a long barrel, as mentioned in the Marty Robbins song, featured in the video game Fallout: New Vegas. It was the style of the time for many to carry shorter barreled guns, often with the front sight filed down or completely off, to aid in a faster draw. So, anyone carrying a long barreled gun was assumed to be confident enough in their ability to handle the gun they would trade the speed of a shorter barrel for accuracy of a longer one.